Treating hydrocarbons



Patented Sept. 8, i953 UNITED STATES PATENT OFFICE TREATING HYDROCARBONS Benjamin L. Moulthrop, Pitman, N. J., assignor to Socony-Vacuum Oil company, Incorporated, a corporation of New-York Application May 20, 1950, Serial No. 163,320

The present invention relates to the treatment of hydrocarbons and mixtures of hydrocarbons to convert sulfhydryls to sulfides andmore particularly to the treatment of sour petroleum fractions containing sulfhydryls to produce sweet petroleum fractions.

It is known that through internal oxidation in the presence of aminophenol, quin-hydrone and similar phenolic oxidation promoters that sulfhydryls can be converted to disulfides. It is also known that the sulfhydryls in gasoline can be extracted with alkaline solutions, the alkaline solutions containing the sulfhydryls, probably as the alkaline metal salts, separated from the treated gasoline and the alkaline solutions regenerated by steaming or by oxidation in the presence of a sulfide of nickel or iron or like metal or in the presence of a phenolic oxidation promoter such as hydroquinone, pyrogallol, polyhydroxy-benzene carboxylic acids or tannins to provide a sweet gasoline and a regenerated extraction solution. It is also known that gasoline can be extracted with alkali metal hydroxide solutions and the fouled solution regenerated simply by blowing air, at atmospheric or super atmospheric pressure, through the fouled solution. It now has been discovered that'gasoline or other mixtures of hydrocarbons containing sulfhydryls can be sweetened or the alkaline solutions employed to extract the sulfhydryls from the mixture of hydrocarbons can be regenerated by oxidation of the sulfhydryls in the presence of certain metallo-organic complexes known as chelates.

It is an object of the present invention to provide a means for sweetening mixtures of hydrocarbons, petroleum fractions and gasoline with chelates. 1

It is another object of the present invention to provide a means for rengerating alkaline solutions which have been used to extract sulfhydryls from mixtures of hydrocarbons, petroleum fractions and gasoline by passing a gas containing free oxygen through said alkaline solution in the presence of at least one chelate.

Other objects and advantages will become apthiophenols. A sour mixture of hydrocarbons, or.

6 Claims. (Cl. 196-29) sour "gasoline or sour kerosene is one containing 'sul'fhydryls. Specifically, sour gasoline is a gasoline which gives a positive reaction in the "doctor test. An alkaline extracting solution is an aqueous solution of an alkali metal hydroxide devoid of '01 containing one or more solutizers. A solutizer is an organic compound, for example alkyl phenols, isobutyric acid, naphthenic acids, etc. which enhances the capability of a solution of alkali metal hydroxide to extract sulfhydr'yls' from a, mixture of hydrocarbons. A fat solution is a sulfhydryl-extracting solution containing sulfhydryls in a concentration such that further use as an extracting medium is not practical. A lean or regenerated solution is a fat alkaline solution which has been treated, i. -e., by steaming or oxidation, to restore its capacity to extract sulfhydryls from mixtures of hydrocarbons. The chelates are metallo-organic compounds of two types. Type I chelates are m'etallo-orga'nic compounds consisting of one molecule of an aromatic aldehyde having a hydroxyl radical in the 'ortho position of the carbonyl group plus one molecule of a dior triprimary amine plus one atomic weight of a metal ion of group eight of the periodic table. Type II chel'ates are metalloorganic compounds consisting of one molecule of anaromatic compound having a hydroxyl group and a nitrosogroup substituted on adjacent carbon atoms of a benzene ring plus one atomic weight of a metal ion of group eight of the periodic table.

In type I chelates the aromatic aldehyde may contain one or more other substituent groups on the benzene ring such as an allyl radical, a halogen, a carboxyl group, a hydroxyl group or a nitro group.

Aldehyde Amine Metal SalicyaIdehyde ethylene diafnine fi E-methyl salicyaldehydeuxl propylene diamine. 2

3-carboxyl salicyoldehyde,

henyleue 'diami e .I. 3-fli1oro salicyaldehyde p n In the type II chelates the ortho nitrosophenol can contain one or more substituent groups on Nitrosophenol O-nitrosophenol S-methyl-fi-nitrosophenol. 4-isopropylfi-nitrosophenol 3-nitroso-salicyclic acid In general, when the presence of the oxidation products of the sulfhydryls can be tolerated in the treated mixture of hydrocarbons, the present invention provides for adding the chelate in an amount of about one pound to about five pounds or more per thousand barrels of hydrocarbon mixture to be treated to the mixture of hydrocarbons to be sweetened. After the addition of the chelate and distribution throughout the mixture of hydrocarbons to be sweetened the treated mixture of hydrocarbons is contacted with a solution of alkali metal hydroxide and then water washed. The alkali metal hydroxide solution can contain from about 5 to about 40 per cent by weight alkali metal hydroxide but it is preferred to use a solution containing about 15 to about 25 weight per cent and particularly about 20 weight per cent alkali metal hydroxide. The solution preferably is an aqueous solution of alkali metal hydroxide but can be one having as the primary solvent water and containing for example alcohol provided the specific gravity of the alkaline solution is such as to permit gravity separation of the treated oil from the alkaline solution.

It is to be noted that the use of more than five pounds per thousand barrels of hydrocarbon mixture is usually accompanied by diminishing returns from an economic viewpoint.

The use of the chelates in the sweetening of gasoline is illustrated by the data present in the following tabulation:

sweetening of sour gasoline Comm" Mercap Addi tration of tan Cow Pre- After Doctor Test five Additive, tent, Wt Treat- Treatof Finished LbsJllllflO Percent S ment ment Gasoline 0. 004 None None Sour. 0.004 do .do Slightly sour. 0 0.004 d Sour.

5 0.004 Sweet. 0 0.003 d S0111. 3 0. 003 Slightly sour. 5 0. 003 d Borderline. 0.003 do .-do-. Sweet.

A=cohalt disalicylal ethylenediamine.

B= 14% cobalt ascobaltus chloride 86% disalicylal propylenediamine.

1 Doctor test immediately after caustic wash.

Caustic wash immediately after addition of additive, 0.2 causticoil ratio; Be caustic; 5 minute contact time.

When the chelate is to be employed in the regeneration of fat alkaline solutions which have been used to extract acidic sulfur compounds, e. g., sulfhydryls, from mixtures of hydrocarbons, the mixture of hydrocarbons to be treated is contacted with a solution, preferably an aqueous solution, of alkali metal hydroxide of conventional strength devoid of or containing one or more solutizers, the alkaline solution is separated from the treated mixture of hydrocarbons and the chelate added. Thereafter, the products of oxidation, organic polysulfides, are separated from the alkaline solution and the regenerated solu- 4 tion is used to extract further amounts of sulfhydryls from a mixture of hydrocarbons.

Thus, for example, an aqueous alkaline solution (6NKOH-2NKAP) containing 0.045 weight per cent butyl mercaptan was regenerated by adding 0.5 weight per cent of cobalt disalicylal ethylene diamine and passing air through the solution. For the purpose of comparing the rates of oxidation in the presence and absence of the chelate, an aqueous alkaline solution (GNKOH- 2NKAP) containing 0.045 weight per cent butyl mercaptan was regenerated by passing air through the solution in the absence of a chelate or other known catalyst. The curves A and B of Figure 1 establish the catalytic effect of the chelate since the slope of curve A is sharper or greater than that of curve B.

(It is to be noted that an aqueous alkaline soluticn (GNKOH-ZNKAP) is a solution contain- ;ing suflicient potassium hydroxide to make the aqueous solution of six normal strength free potassium hydroxide and sufficient of the potassium salts of alkyl phenols to make the solution of two normal strength.)

Iclaim:

l. A method of converting a sulfhydryl to a sulfide which comprises contacting a, sulfhydryl with an oxygenated chelate of a metal selected from the group consisting of iron, cobalt, nickel and palladium in the presence of aqueous alkaline solution of an alkali metal hydroxide.

2. A method of sweetening petroleum fractions which comprises adding an oxygenated chelate of a metal selected from the group consisting of iron, cobalt, nickel and palladium to a petroleum fraction and contacting said petroleum fraction containing said oxygenated chelate with an aqueous alkaline solution of an alkali metal hydroxide.

3. A method of sweetening gasoline which comprises mixing an oxygenated chelate of a metal selected from the group consisting of iron, cobalt, nickel and palladium with a, sour gasoline at a rate of about 1 to about 5 pounds of chelate per 1000 barrels of gasoline and contacting said gasoline containing said oxygenated chelate with an aqueous alkaline solution of an alkali metal hydroxide.

4. In the regeneration of aqueous alkaline solutions which have been used to extract weakly acidic sulfur compounds from hydrocarbon mixtures comprising contacting an aqueous alkaline solution containing weakly acidic sulfur com pounds with an oxidizing gas containing free oxygen to convert said weakly acidic sulfur compounds into substantially water-insoluble sulfur compounds and separating said substantially water-insoluble sulfur compounds from said aqueous alkaline solution, the improvement which comprises passing said oxidizing gas containing free oxygen through said aqueous alkaline solution in the presence of a chelate of a metal selected from the group consisting of iron, cobalt, nickel and palladium.

5. In the regeneration of aqueous alkaline solutions which have been used to extract mercaptans from hydrocarbon mixtures and contain said mercaptans as mercaptides comprising: contacting an aqueous alkaline solution containing mercaptides with an oxidizing gas containing free oxygen to convert said mercaptides to polysulfides and separating said polysulfides from said aqueous alkaline solution, the improvement which comprises oxidizing said mercaptides to polysulfides in the presence of an amount of a chelate of a metal selected from the group consisting of iron, cobalt, nickel and palladium sufficient to accelerate the oxidation of said mercaptides.

6. In the regeneration of alkaline solutions which have been used to extract mercaptans from hydrocarbon mixtures and contain said mercaptans as mercaptides comprising: contacting an alkaline solution containing mercaptides with an oxidizing gas containing free oxygen to convert said mercaptides to polysulfides and separating said polysulfides from said alkaline solution, the improvement which comprises oxidizing said mercaptides to polysulfides in the presence of at least about 0.5 weight per cent of a chelate of a metal selected from the group consisting of iron, 15

cobalt, nickel and palladium.

BENJAMIN L. MOULTI-IROP.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,081,801 Wohl Dec. 16, 1913 2,302,352 Schultze Nov. 1'7, 1942 2,450,276 Folger Sept. 28, 1948 2,494,687 Bond Jan. 17, 1950 2,523,549 Axe Sept. 26, 1950 OTHER REFERENCES Calvin et al., J. A. C. 8., vol. 68, pages 2254- 2256 (1946). 

1. A METHOD OF CONVERTING A SULFHYDRYL TO A SULFIDE WHICH COMPRISES CONTACTING A SULFINYDRYL WITH AN OXYGENATED CHELATE OF A METAL SELECTED FROM THE GROUP CONSISTING OF IRON, COBALT, NICKEL AND PALLADIUM IN THE PRESENCE OF AQUEOUS ALKALINE SOLUTION OF AN ALKALI METAL HYDROXIDE.
 2. A METHOD OF SWEETENING PETROLEUM FRACTIONS WHICH COMPRISES ADDING AN OXYGENATED CHELATE OF A METAL SELECTED FROM THE GROUP CONSISTING OF IRON, COBALT, NICKEL AND PALLADIUM TO A PETROLEUM FRACTION AND CONTACTING SAID PETROLEUM FRACTION CONTAINIG SAID OXYGENATED CHELATE WITH AN AQUEOUS ALKALINE SOLUTION OF AN ALKALI METAL HYDROXIDE. 